1. Field of the Invention
The present invention generally relates to focal plane array processing systems and techniques and more specifically, to an infrared focal plane array dual processing system and technique capable of simultaneous temporal and image processing from a single infrared focal plane array.
2. Description of Related Prior Art
Infrared imaging devices operate at a specific wavelength region, spatial resolution and frequency response determined by such major factors as the spectral, spatial, and temporal response of the detector. An infrared focal plane array is the surface upon which radiation will impinge upon to be detected by the device. Detector elements may be integral with the array to convert the radiation to electrical signals. By use of signal processing incorporated into the electronics of the infrared imaging device, there can be achieved the enhancement or reduction of features in the produced output.
Two types of generalized processing capabilities of an infrared focal plane array detector are image and temporal processing. Image processing includes not only imaging (display) but also intelligent processes such as pattern recognition. Temporal processing is implemented for such purposes as spectral estimation. Sampling frequencies for the two types of processing generally require different frequencies because of the nature of the signature of interest. Image processing generally requires a sampling frequency equal to a video rate, typically 30 hertz. A temporal sampling frequency, is usually greater than the imaging sampling frequency since information gained from the temporal domain require a larger data sample. In the prior art, separate systems are required for implementation of both processing capabilities.
Currently, two systems are required in order to provide thermal imagery of a scene as well as temporal processing of selected areas in the scene. One of the systems is an imaging system, typically a scanned forward-looking infrared (FLIR) system. The complimentary system is a co-boresighted, non-imaging infrared (IR) device which temporally processes subareas of the field of view of the imaging FLIR. Both systems require front-end optics, detector cooling apparatus and a great deal of common electronics. Disadvantages arise from the use of the above prior art devices. Typically, two distinct co-boresighted systems are mounted on a host platform that is subject to vibration. The ability to economically provide line-of-sight motion compensation and maintain boresight between two distinct systems is compromised in practice by jitter introduced by vibrating host platforms. The temporal processing system is extremely sensitive to jitter induced by the host platform. Jitter rejection by the temporal processing system is crucial to achieving high temporal processing performance, known as temporal signal fidelity. Expensive and complicated stabilization schemes are generally required to attenuate jitter and maintain boresight since the use of elastomer damping to achieve vibration isolation does not allow the boresight tolerances required in a high performance system.
While the prior art has reported using separate imaging and temporal processing systems and technique, none have established a basic for a specific apparatus that is dedicated to the task of resolving the particular problem at hand.
What is needed in this instance is a dual processing system and technique utilizing a single focal plane array such that there is substantially no temporal signal fidelity degradation when operated.